The Reaction Mechanism
The Reaction Mechanism of Formaldehyde by Photocatalyst
(source: http://www.photocatalyst.co.jp)
The oxidizing power of the intermediates is very powerful, it is able to oxidize organics such as PCBs (polychlorinated biphenyl) and other POPs (Persistent Organic Pollutants) e.g. dioxins, in ambient temperature. For those who wants to know more about PCBs, please visit: http://en.wikipedia.org/wiki/Polychlorinated_biphenyl
Therefore, the photocatalyst can be applied in wastewater treatment, flue gas of incinerator or automobile treatment. In addition, not only can the photocatalyst kill the bacteria and virus, but also decompose the toxin they generate. Thus, it can be applied in bacteria control, SARS or flu prevention in hospitals and household.
The following table compares the oxidation potential of the common oxidizing reagents or intermediates with chlorine:
Compounds Oxidation potential Relative power
(volts) of chlorine
Fluorine 3.06 2.25
Hydroxyl radical (OH*) 2.80 2.05
Atomic oxygen (O*) 2.42 1.78
Ozone 2.07 1.52
Hydrogen peroxide 1.77 1.30
Perhydroxyl radical 1.70 1.25
Permanganate 1.67 1.23
Chlorine oxide 1.50 1.10
Hypochlorous Acid 1.49 1.10
Chlorine 1.36 1.0
...
...
Oxygen 0.40 0.29